"A preliminary cause of death is that Martinez died of cardiac arrest and multiple organ failure," he said. An autopsy was pending.

On Tuesday, Harris County sheriff's officials announced Martinez had been charged with capital murder in the death of Jacqueline Anderson. She was found bound with rope and strangled in her north suburban Houston home after she apparently interrupted a burglary in 1987.

Deputies say Martinez, a neighbor at the time, confessed to breaking into the house but contended Anderson was alive when he fled.

The sheriff's office reopened the case last year and DNA evidence linked him to the slaying scene.

Martinez had a lengthy criminal history that extended back to the 1950s and included burglaries, thefts, drug possession, aggravated robbery and rape. He also was a registered a registered sex offender in El Paso.

In 1989, Martinez was sentenced to 40 years in prison for a Harris County burglary with intent to commit theft. He was released on mandatory supervision in October 2005, prison records show. In early May, he was placed in the South Texas Intermediate Sanction Facility as a parole violator.